This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Tip growth and cell motility are highly directed forms of cellular motion. Tip growth is a form of polarized growth where exocytosis, leading to cell expansion, occurs at a single localized site, giving rise to long cylindrical or conical structures. Invasion by many pathogenic fungi and reproduction of higher plants is dependent on tip growth. Cell motility on the other hand involves migration of the entire cell. Many types of cells are able to migrate, including supporting glia of the nervous system, macrophages of the immune system and cancer cells. Both tip growth and cell motility can be directed by external cues to guide a population of cells that would normally grow/move in random directions. Our research has focused on the ionic control and signal transduction pathways that direct normal tip growth and cell motility during the imposition of external guidance cues.